An advent calendar of sorts Day 17. Yo! Saturnalia.

December 17 was the Roman festival of Saturnalia, which has given rise to many of the traditions associated with Christmas today.

The Roman god Saturn

For example, there was always a huge feast at which masters and slaves changed places, with the masters serving the slaves. There is an echo of this custom in the Royal Navy, where officers serve the lower ranks their dinner on Christmas Day.

The day was a public holiday and even schools were closed. Gifts were exchanged and everyone was supposed to have fun. Everyone wore their best clothes and togas - a symbol of rank - were forbidden. Instead everybody wore the 'freedman' hat.

A Saturnalian prince was chosen from among the youngest members of the family and he ruled over the rest for the day. 

The correct greeting was 'Io, Saturnalia!' (Meaning Ho - praise to Saturn.)  It was pronounced Yo. 

So... Yo! Saturnalia to you all.